This invention relates in general to work feeders for sewing machines and in particular to an improved and simplified top work feeder.
From the early days of their development, sewing machines have been provided with a lower feed mechanism which is usually located in an opening in the work surface of the machine adjacent the stroke of the sewing machine needle or needles. Generally, these feeders have upwardly-facing serrated surfaces which cyclically engage and advance the lowermost surface of the layers of material being sewn in synchronism with the stitching stroke of the needle.
In those early days it was left to the skill of the operator to advance or retard the movement of the upper layers of the material being sewn and to smooth wrinkles in order that they would be sewn in proper unison with the lower layer or layers. Several attempts have been made to simplify the operator's task and to provide a more uniform output by automating the feed of the upper layers of material being sewn and to coordinate that feed with the lower feed. One of the earliest attempts involved a flexible cable drive for the top feeder, the flexible cable being synchronized as well as possible with the drive of the bottom feeder. The results obtained were not always uniformly good and the complexity and interference with sewing operations caused by the flexible cable apparatus precluded its widespread adoption.
More recently, U.S. Pat. Nos. 3,530,809 and 3,995,571 issued to the present inventor and the arrangements described and claimed in those patents have enjoyed substantial success. The disclosures of those two patents are incorporated herein by reference to serve as background. However, several years' experience with the devices which constitute the subject matter of those two patents has indicated that a further simplification and improvement of top feeding is feasible. Accordingly, the primary object of the present invention is the reduction of noise and wear in top feeding devices. A further object is more uniform and consistent positive feeding of materials. Another object is the reduction of complexity and the further clearing of work space in and about top feeding apparatus in sewing machines.